It's one extra level of indirection. In the housing market, landlords do sometimes pay for upgrades to their rental properties, but they are less likely to do so than owner-occupiers.

Additionally if the ship owner was also the operator, they could benefit from some vertical integration, training their crew on the new technology.

If the effect of the kites on prices becomes large enough or the technology becomes standard, expect widespread adoption, but it's a reasonable claim that the existing market structure slows rollout when it's only marginally profitable.